There are a large number of websites on the Internet and these websites publish a wide variety of information. A user terminal connected to the Internet accesses a website by specifying a URL (Uniform Resource Locator) of the website by a web browser, so that the user terminal can display a web page provided from the website. Thereby, a user of the user terminal can browse information posted on a web page provided from the website. Therefore, it is important for a provider of the information posted on the webpage to know the level of interest of the user (degree of interest) in the web page and the information posted thereon.
Conventionally, the user's degree of interest is determined on the basis of the browsing time of the web page (staying time in the web page). In this method, the longer the browsing time of the web page, the higher the user's degree of interest is determined to be. For example, Patent Document 1 discloses a technique for measuring an elapsed time by using transition of a web page as an end event and transmitting the elapsed time to a server as the browsing time of each web page.